Virucidal effects of rodent cage-cleaning practices on the viability of adenovirus vectors
Related Experiment Video
Updated: Sep 29, 2026
Handling of the Cotton Rat in Studies for the Pre-clinical Evaluation of Oncolytic Viruses
Published on: November 24, 2014
Jacqueline D Porter1, Russette M Lyons
1Genetic Therapy, Inc., 9 W. Watkins Mill Road, Gaithersburg, Maryland 20878, USA.
Abstract:
Human adenoviruses and adenoviral vectors are classified as Risk Group 2 agents and require BSL2 containment and practices. An additional consideration in using adenoviruses and viral vectors in laboratory animal studies is the possible transmission of these agents to other animals and/or personnel as a result of viral shedding in animal urine and feces. When handling BSL2 agents, cage-wash staff are required to wear appropriate personnel protective equipment, including scrubs, Tyvek suit, hair covering, dust mask, shoes covers, and gloves. Current decontamination procedures are to bag and autoclave soiled rodent cages containing bedding prior to washing in the cage washer to prevent possible adenoviral transmission. However, the practice of autoclaving softens the polycarbonate-based rodent cages, allowing damaging agents or conditions to affect the integrity of the plastic and degrade the cages. The objective of this study was to determine whether current rodent cage-cleaning practices produced virucidal effects for use in lieu of or prior to autoclaving the cages. We found that heating an Av3GFP vector in a test tube to a temperature of 74 degrees C (165 degrees F) for 6 min conditions equivalent to those of the cage washer resulted in greater than an 11-log reduction in infectivity of the vector as evaluated by its cytopathic effect on cells. The combination of heating and a liquid, phosphate-free alkaline detergent produced the same reduction in vector infectivity. However, common cage-cleaning solutions alone possessed no virucidal activity. The high temperatures used in cage-washing procedures alone or in combination with a cleaning solution reduced or eliminated the risk of transmission from viral shedding through urine and feces even at vector concentrations far greater than would ever be expected to be present. Autoclaving cages diminishes the stability and integrity of the polycarbonate cages without providing a further reduction in the risk of virus or vector transmission. On the basis of results from this study, new cage-wash recommendations include dumping the contaminated bedding into a HEPA-filtered waste disposal system and autoclaving the bags of bedding before disposal, then cleaning the cages in the rack washer at wash temperatures of 74 degrees C (165 F) and rinse temperatures of 82 degrees C (180 F).
Insights
Autoclaving rodent cages degrades plastic. High-temperature cage washing effectively inactivates adenoviral vectors, eliminating the need for autoclaving and preserving cage integrity. This improves laboratory safety and equipment longevity.
Area of Science:
- Virology and Laboratory Animal Science
- Biosafety and Decontamination Protocols
Background:
- Human adenoviruses and adenoviral vectors are Risk Group 2 agents requiring BSL2 containment.
- Viral shedding in animal waste poses transmission risks to other animals and personnel.
- Current autoclaving of rodent cages before washing degrades polycarbonate, compromising cage integrity.
Purpose of the Study:
- To evaluate if current rodent cage-cleaning practices achieve virucidal effects.
- To determine if cage washing can replace or precede autoclaving for adenoviral decontamination.
Main Methods:
- An Av3GFP adenoviral vector was heated to 74°C (165°F) for 6 minutes, simulating cage washer conditions.
- The vector's infectivity was assessed by cytopathic effect on cells after treatment.
- The effect of heating alone, heating with alkaline detergent, and detergent alone was evaluated.
Main Results:
- Heating the vector to 74°C for 6 minutes resulted in >11-log reduction in infectivity.
- The combination of heat and phosphate-free alkaline detergent yielded similar reductions.
- Cage-cleaning solutions alone showed no virucidal activity; autoclaving offered no additional risk reduction.
Conclusions:
- High-temperature cage washing (74°C wash, 82°C rinse) effectively inactivates adenoviral vectors, mitigating transmission risks.
- Cage washing alone is sufficient for decontamination, preserving cage integrity and eliminating the need for autoclaving.
- Recommended practice: HEPA-filter bedding disposal, bag bedding autoclaving, followed by high-temperature cage washing.
